Spanish patent application No. 200400773 of the same applicants describes a variable speed handrail for variable speed walkways and mechanical stairs, which are formed by a flexible profile circulating along the walkway or stairs and moving all along its path at a constant speed, and by many independent handgrips coupled on the flexible profile moving at a speed considerably equal to the speed of the transporting plates closest to the walkway or stairs, so that they will have to move at a slow speed in some sections, at a faster speed in other sections and at a variable speed in intermediate sections.
The handrail previously mentioned comprises a series of carriages with a handgrip joined to each one of them. Each carriage is driven along the path of the handrail and bears means for locking and unlocking the carriage to a drive chain of the handrail at a constant speed and to couple and uncouple the carriage to a variable pitch screw in order to move said carriage at a variable speed. These means are actuated by means of a horizontal axis free turning wheel which is assembled in the body of the carriage and is intended to be supported against a cam profile of the guide, located in the sections in which the transition from movement at a constant speed to a variable speed is to occur.
The carriage is formed by a vertical plate bearing horizontal axis leading rollers supported on a guide next to the handrail, running therein, to drive said carriage along the path of the handrail.
The means for locking and unlocking the carriage to the drive chain at a constant speed consists of a locking tooth which can be moved linearly in a vertical direction, between a locking or an active upper position, in which said tooth is anchored to the drive chain, and a lower position, in which said tooth is separated and unlocked from the chain. In the second position mentioned, the unlocking position, the coupling of the carriage to one of the variable pitch screws of the walkway arranged in variable speed sections occurs. To that end, the carriage bears an arm laterally projecting from the plate forming the body of said carriage and is positioned so that it is coupled or engaged with the screws when the carriages move in coincidence with the positions of these screws, in which the unlocking of the tooth in relation to the chain also occurs.
As has been indicated, the locking and unlocking of the carriage with the drive chain of the handrail is carried out by means of the linear movement of a tooth, which movement can present operative problems for the carriage.
Furthermore, the carriage described above must have auxiliary parts for supporting the rollers of the chain in the unlocking position between carriage and chain.